1. Field of the Invention
The present invention relates to devices for storing and displaying digital data by means of fluid markers which are caused to undergo displacements within a capillary space delimited by two confinement plates. The fluid which constitutes the markers shares the volume of the capillary space with a second fluid which is not miscible with the first fluid in order to ensure durable splitting into two phases. The heterogeneous fluid layer which is pinched or "squeezed" between the two confinement plates is therefore formed of a globular phase on each side of which is located an adjacent interstitial phase. The volume of each globule is such as to be squeezed between the confinement plates. This globule thus constitutes a marker which has two degrees of freedom and which is capable of displacement within the area of the capillary space, of taking up a fixed position while forming capture zones therein and of interacting with other globules which perform the function of a reverse supply of fluid.
2. Description of the Prior Art
Fluid displacement devices which do not require mechanical elements such as pistons, pumps, turbines, and so on, are usually based on the modification of the physicochemical properties of the fluids to be displaced. It is possible to contemplate the use of means such as thermosiphons, convectors, evaporators, circulators based on electroconvection or on magnetohydrodynamics. The disadvantage of these means, however, is that they call for relatively high power consumption since different potential applications entail the need to circulate an electric current, to produce a magnetic field, to produce an expansion, to produce thermal or electrical contraction, to produce a change in phase of a substance, and so on.
The problem presented by the displacement of a fluid by means of an electrical control system without having recourse to mechanical elements while at the same time ensuring low power consumption presupposes that it is possible to generate sufficient driving power to overcome forces other than forces of gravity.
A device for indicating fluid displacement must in fact be capable of operating correctly in all positions and to withstand accelerations without any difficulty. In consequence, position maintenance of the fluid must be dependent on forces such that inertia forces may be considered negligible in comparison. These forces must be overcome by a force of electrical origin which limits power consumption to a strict minimum.
The present invention proposes to solve this problem by utilizing surface tension forces, interfacial tension forces and forces arising from electric polarization of a dielectric fluid. The surface tension forces ensure position maintenance of small quantities of fluid flowing within a capillary space of small height since gravitational forces become negligible with respect to the capillary forces. The forces generated by polarization of a dielectric attain high values when the electric field gradient is very high, which can readily be obtained by means of a voltage applied to closely spaced electrodes. This technique does not entail the need to pass an electric current through the fluid either before, during or after its displacement.